Reflective communication using radio-frequency devices

• US 7,844,221 B2
• Filed: 09/14/2007
• Issued: 11/30/2010
• Est. Priority Date: 06/04/2002
• Status: Expired due to Fees

• Current Assignee: Mineral Lassen LLC (Intellectual Ventures LLC)
• Original Assignee: Mineral Lassen LLC (Intellectual Ventures LLC)
• Inventors: Forster, Ian J.
• Primary Examiner(s): Pan; Yuwen
• Application Number:
  US11/855,933
• Publication Number:
  US 20080043820A1
• Time in Patent Office: 1,173 Days
• Field of Search: 455/41.1
• US Class Current: 455/41.1
• CPC Class Codes: G01S 13/003 Bistatic radar systems; Multistatic radar systems
• CPC Class Codes: G01S 13/325 using transmission of coded signals, e.g. P.S.K. signals
• CPC Class Codes: G01S 13/756 using a signal generator for modifying the reflectivity of the reflector G01S13/758 takes precedence
• CPC Class Codes: G01S 13/758 using a signal generator powered by the interrogation signal
• CPC Class Codes: G01S 13/878 Combination of several spaced transmitters or receivers of known location for determining the position of a transponder or a reflector G01S13/874 takes precedence
• CPC Class Codes: G06K 17/0022 arrangements or provisious for transferring data to distant stations, e.g. from a sensing device "transfer between computer elements G06F13/00 "; data-transmission H04L
• CPC Class Codes: G06K 7/0008 General problems related to the reading of electronic memory record carriers, independent of its reading method, e.g. power transfer
• CPC Class Codes: G06K 7/10079 the collision being resolved in the spatial domain, e.g. temporary shields for blindfolding the interrogator in specific directions
• CPC Class Codes: G06K 7/10316 using at least one antenna particularly designed for interrogating the wireless record carriers antennas in general H01Q1/22
• CPC Class Codes: G06K 7/10346 the antenna being of the far field type, e.g. HF types or dipoles

Abstract

The present invention relates to a reflective communication system that allows information from wireless communication devices, such as radio-frequency identification devices (RFID), to be reflectively communicated to a receiver in lieu of using a separate communication system. A transmitter transmits a communication signal, having a carrier frequency, to the wireless communication device to provide power. The wireless communication device modulates a data signal onto the communication signal to form a reflected data signal. The wireless communication device reflects the reflected data signal directly to the receiver. In this manner, the process of communicating information from a wireless communication device is accomplished in one communication system rather than two. If the receiver also directly receives the communication signal from the transmitter, the receiver can determine the location of the wireless communication device relative to the transmitters.

Claims

1. A reflective communication system, comprising:

a plurality of transmitters configured to operate on the same frequency, wherein each transmitter of the plurality of transmitters is physically separate from the rest of the plurality of transmitters, and wherein each transmitter of the plurality of transmitters is configured to transmit a communication signal that is spread with a spread spectrum code associated with the transmitter;

a plurality of wireless communication devices located in the transmission field of the plurality of transmitters and configured to receive communication signals transmitted from the plurality of transmitters, wherein the plurality of wireless communication devices are further configured to reflectively modulate the communication signals with data signals having a modulation to form reflected data signals; and

a receiver configured to;

store, in a receiver memory, a spread spectrum coding sequence containing a plurality of receiver spread spectrum codes, wherein each receiver spread spectrum code correlates to a spread spectrum code respectively associated with a transmitter of the plurality of transmitters;

store, in the receiver memory, information indicating a physical location of each transmitter of the plurality of transmitters;

receive the communication signals transmitted from the plurality of transmitters;

receive the reflected data signals from the plurality of wireless communication devices; and

for each reflected data signal that is received;

determine the communication signal that was reflectively modulated to form the reflected data signal;

determine a time delay between receipt of the reflected data signal and receipt of the determined communication signal;

determine the spread spectrum code that was used to spread the determined communication signal, wherein the spread spectrum code is determined using the spread spectrum coding sequence stored in the receiver memory;

using the determined spread spectrum code, determine which of the plurality of transmitters transmitted the determined communication signal; and

determine an approximate location of the wireless communication device that formed the reflected data signal based on the determination of the transmitter that transmitted the determined communication signal, the determined time delay, and the stored information indicating the physical location of the transmitter that transmitted the determined communication signal.

2. The system of claim 1, wherein the receiver is further configured to remove the modulation from the reflected data signals to form data.

3. The system of claim 2, wherein the receiver further comprises a demodulator configured to demodulate the modulation from the reflected data signals to form the data.

4. The system of claim 1, wherein the receiver is further configured to mix the receiver spread spectrum codes from the spread spectrum coding sequence with the reflected data signals to recover the reflected data signals in an unspread format.

5. The system of claim 1, wherein to determine the spread spectrum code that was used to spread the determined communication signal, the receiver is further configured to choose a receiver spread spectrum code and determine whether the chosen receiver spread spectrum code successfully despreads the determined communication signal.

6. The system of claim 1, wherein the receiver is further configured to determine the approximate location of the wireless communication device by triangulating at least two different communication signals received from at least two different transmitters with the corresponding reflected data signals using the determined time delays between receipt of each of the two different communication signals and the corresponding reflected data signals.

7. The system of claim 1, wherein the plurality of transmitters and the receiver are combined into a single transceiver.

8. A reflective communication system, comprising:

a plurality of transmitters, wherein each transmitter is configured to transmit a communication signal that is spread according to a different frequency-hopping sequence, wherein each transmitter of the plurality of transmitters is physically separate from the rest of the plurality of transmitters;

a plurality of wireless communication devices located in the transmission field of the plurality of transmitters and configured to receive communication signals transmitted from the plurality of transmitters, wherein the plurality of wireless communication devices are further configured to reflectively modulate the communication signals with data signals having a modulation to form reflected data signals; and

a receiver configured to;

store, in a receiver memory, a plurality of frequency-hopping sequences, wherein each sequence is associated with one transmitter of the plurality of transmitters;

store, in the receiver memory, information indicating a physical location of each transmitter of the plurality of transmitters;

receive the communication signals from the plurality of transmitters;

receive the reflected data signals from the plurality of wireless communication devices; and

for each reflected data signal that is received;

determine the communication signal that was reflectively modulated to form the reflected data signal;

determine a time delay between receipt of the reflected data signal and receipt of the determined communication signal;

determine the frequency-hopping sequence that was used to spread the determined communication signal, wherein the frequency-hopping sequence is determined using the plurality of frequency-hopping sequences stored in the receiver memory;

determine, using the determined frequency-hopping sequence, which of the plurality of transmitters transmitted the determined communication signal; and

determine an approximate location of the wireless communication device that formed the reflected data signal based on the determination of the transmitter that transmitted the determined communication signal, the determined time delay, and the stored information indicating the physical location of the transmitter that transmitted the determined communication signal.

9. The system of claim 8, wherein the receiver is further configured to remove the modulation from the reflected data signals to form data.

10. The system of claim 9, wherein the receiver further comprises a demodulator configured to demodulate the modulation from the reflected data signals to form the data.

11. The system of claim 8, wherein to determine the frequency-hopping sequence that was used to spread the determined communication signal, the receiver is further configured to choose a frequency-hopping sequence and determine whether the chosen frequency-hopping sequence successfully despreads the determined communication signal.

12. The system of claim 8, wherein the receiver is further configured to determine the approximate location of the wireless communication device by triangulating at least two different communication signals received from at least two different transmitters with the corresponding reflected data signals using the determined time delays between receipt of each of the two different communication signals and the corresponding reflected data signals.

13. A method of determining the origination of a data signal reflected by a wireless communication device that uses a communication signal from a transmitter as a communication medium, the method comprising:

storing, in a memory, a spread spectrum coding sequence containing a plurality of receiver spread spectrum codes, wherein each receiver spread spectrum code correlates to a spread spectrum code that is respectively associated with a transmitter of a plurality of transmitters;

storing, in the memory, information indicating a physical location of each transmitter of the plurality of transmitters;

receiving communication signals that are transmitted on a same frequency from the plurality of transmitters, wherein each transmitted communication signal is spread with a different spread spectrum code, and wherein each transmitter of the plurality of transmitters is physically separate from the rest of the plurality of transmitters;

receiving reflected data signals from a plurality of wireless communication devices, wherein the reflected data signals are formed by the wireless communication devices by reflectively modulating the communication signals with data signals; and

for each reflected data signal that is received;

determining the communication signal that was reflectively modulated to form the reflected data signal;

determining a time delay between receipt of the reflected data signal and receipt of the determined communication signal;

determining the spread spectrum code that was used to spread the determined communication signal, wherein the spread spectrum code is determined using the spread spectrum coding sequence stored in the receiver memory;

using the determined spread spectrum code, determining which of the plurality of transmitters transmitted the determined communication signal; and

determining an approximate location of the wireless communication device that formed the reflected data signal based on the determination of the transmitter that transmitted the determined communication signal, the determined time delay, and the stored information indicating the physical location of the transmitter that transmitted the determined communication signal.

14. The method of claim 13, further comprising demodulating the reflected data signals to form data.

15. The method of claim 13, further comprising mixing the receiver spread spectrum codes from the spread spectrum coding sequence with the reflected data signals to recover the reflected data signals in an unspread format.

16. The method of claim 13, wherein said determining the spread spectrum code that was used to spread the determined communication signal further comprises choosing a receiver spread spectrum code and determining whether the chosen receiver spread spectrum code successfully despreads the determined communication signal.

17. The method of claim 13, further comprising determining the approximate location of the wireless communication device by triangulating at least two different communication signals received from at least two different transmitters with the corresponding reflected data signals using the determined time delays between receipt of each of the two different communication signals and receipt of the corresponding reflected data signals.

18. A method of determining the origination of a data signal reflected by a wireless communication device that uses a communication signal from a transmitter as a communication medium, the method comprising:

storing, in a memory, a plurality of frequency-hopping sequences, wherein each sequence is associated with one transmitter of a plurality of transmitters;

storing, in the memory, information indicating a physical location of each transmitter of the plurality of transmitters;

receiving, from a plurality of transmitters, communication signals that are spread according to different frequency-hopping sequences, wherein each transmitter from the plurality of transmitters is physically separate from the rest of the plurality of transmitters;

receiving reflected data signals from a plurality of wireless communication devices, wherein the reflected data signals are formed by the wireless communication devices by reflectively modulating the communication signals with data signals; and

for each reflected data signal that is received;

determining the communication signal that was reflectively modulated to form the reflected data signal;

determining a time delay between receipt of the reflected data signal and receipt of the determined communication signal;

determining the frequency-hopping sequence that was used to spread the determined communication signal, wherein the frequency-hopping sequence is determined using the plurality of frequency-hopping sequences stored in the receiver memory;

determining, using the determined frequency-hopping sequence, which of the plurality of transmitters originated the communication signal; and

determining the approximate location of the wireless communication device that formed the reflected data signal based on the determination of the transmitter that originated the determined communication signal, the determined time delay, and the stored information indicating the physical location of the transmitter that originated the determined communication signal.

19. The method of claim 18, further comprising demodulating the reflected data signals to form data.

20. The method of claim 18, wherein said determining the frequency-hopping sequence that was used to spread the determined communication signal further comprises choosing a frequency-hopping sequence and determining whether the chosen frequency-hopping sequence successfully despreads the determined communication signal.

21. The method of claim 18, further comprising determining the approximate location of the wireless communication device by triangulating at least two different communication signals originated by at least two different transmitters with the corresponding reflected data signals using time delays between each of the two different communication signals and the corresponding reflected data signals.

22. A reflective communication system for determining the origination of a data signal reflected from a wireless communication device of a plurality of wireless communication devices that use communication signals from a plurality of transmitters as a communication medium, wherein each transmitter of the plurality of transmitters is physically separate from the rest of the plurality of transmitters, the system comprising:

means for storing a spread spectrum coding sequence containing a plurality of receiver spread spectrum codes, wherein each receiver spread spectrum code correlates to a spread spectrum code respectively associated with a transmitter of the plurality of transmitters;

means for storing information indicating a physical location of each transmitter of the plurality of transmitters;

means for receiving communication signals transmitted from the plurality of transmitters;

means for receiving reflected data signals that are reflectively transmitted by the plurality of wireless communication devices based on the communication signals transmitted from the plurality of transmitters;

means for determining the communication signal that was reflectively modulated to form the reflected data signal for each reflected data signal that is received;

means for determining a time delay between receipt of the reflected data signal and receipt of the determined communication signal for each reflected data signal that is received;

means for determining the spread spectrum code that was used to spread each of the determined communication signals, wherein the spread spectrum code is determined using the stored spread spectrum coding sequence;

means for determining which of the plurality of transmitters transmitted each of the determined communication signals using the respective determined spread spectrum code; and

means for determining an approximate location of the wireless communication device based on the determination of each of the transmitters that transmitted the determined communication signals, the determined time delays, and the stored information indicating the physical location of the transmitters that transmitted the determined communication signals.